Memory card adapter insertable into a motherboard memory card socket comprising a memory card receiving socket having the same configuration as the motherboard memory card socket

ABSTRACT

A memory card adapter and method is provided which can add features or provide functions to a computer system&#39;s memory modules without having to replace and discard existing memory modules. An adapter is provided which has electrical contacts that are capable of being plugged into a memory module receiving socket of a motherboard and a memory module receiving socket capable of receiving and retaining a memory module such as a SIMM. The adapter has logic, circuitry and/or memory chips to add new function to the existing memory module and also has all information and hardware needed for proper interface with the motherboard of the computer system. The present invention can add a variety of function such as parity, error correction code and error correction code on SIMM as well as convert signals which form from the system for use on the SIMM which signals in the form generate by the computer are not compatible with the SIMM.

FIELD OF THE INVENTION

The present invention relates to computer memory devices, and moreparticularly to a memory extension adapter apparatus for memory cardsthat allows parity or error correction code ("ECC") or function to beadded to memory cards that do not have these capabilities.

BACKGROUND OF THE INVENTION

Computer systems utilize various integrated circuit devices for datastorage and retrieval. Traditionally, a computer system's random accessmemory (RAM) primarily included a plurality of single bit integratedmemory chips connected directly to the computer system's centralprocessing unit ("CPU") motherboard. As computing technology improved,computer systems required more memory to support the varioustechnological improvements. Thus, to expand the system memory of acomputer, manufacturers began incorporating memory sockets into themotherboard capable of receiving memory modules on which memory chipshad been mounted. This allowed for a computer system's memorycapabilities to be expanded by addition of memory modules.

These memory modules are commonly referred to as single in-line memorymodules ("SIMMs") with their plug-in socket referred to as a SIMMsocket. By plugging a SIMM into a SIMM socket, the memory capacity of acomputer system can be easily expanded. Currently, most computer systemsare manufactured with several SIMM sockets included on the motherboardof the computer so that a computer user can add additional memory to thesystem as needed.

SIMMs are printed circuit boards ("PCB"s) built with memory chipsmounted to the PCB and having connection pins along one edge of the PCB.The standard SIMM size is either a 30 pin version or a 72 pin version.The organization of a SIMM is described as the depth of the module bythe width of module. The depth portion of this organization refers tothe depth of memory chips located on the module. The width describes howmany bits can be accessed at the same time by the computer system. Thus,for example, a "4Mx8" SIMM is 4 MEGA address deep and 8 bits wide. Whilethe standard memory module allows the amount of system memory to beupgraded, these modules do not allow any of the other functions of thesystem to be updated, nor do the modules add any new functions besidesincreased memory. Furthermore, the modules themselves cannot have theirfunction upgraded. Thus, while the amount of available memory may beexpanded by the addition of memory modules, the modules do not add newfunction to the system.

For example, parity or ECC functions cannot be added to SIMMs in orderto upgrade the memory module and accordingly add these features to acomputer system. If the features of a memory module are desired to beupgraded, an all-new memory card having the desired function(s) must besubstituted into the computer system with the existing module beingremoved and discarded. Thus, the old SIMMs must be completely discardedand replaced to add new features to a computer system by way of a memorymodule.

Currently, the most common type of a memory SIMM is the so-called "x32SIMM" which is a non-parity in-line memory module. A x32 SIMM containsenough DRAMs to support the reading and writing of 8 data bits per byte,but does not support any other functions such as parity, ECC, ECC onSIMM, non-standard interface levels or non-standard voltage powersupplies. Therefore, to be able to upgrade a computer system that usesx32 SIMMs to have parity, ECC, ECC on SIMM or other new and addedfunctions, the x32 SIMMs must be discarded and replaced with entirelynew SIMMs having the desired configuration and features.

Thus, since existing SIMMs must be discarded in order to upgrade memorymodule features and functions, there exists a need for a memory moduleadapter with added features such as parity, ECC, ECC on SIMM,non-standard interface levels and/or non-standard power supplies whichis configured to add these functions to existing memory modules lackingthese functions so that existing memory modules do not have to bereplaced.

SUMMARY OF THE INVENTION

The apparatus of this invention provides a memory adapter with addedfeatures such as parity or error correction code. The adapter has anelectrical edge connector along a first edge which is capable ofplugging into a standard memory card socket located on a computersystem's motherboard. Opposite the edge of the adapter having theelectrical edge connector, the adapter has a card receiving socketcapable of receiving an in-line memory module. The existing SIMM isplugged into this socket located on the adapter. The adapter containsall logic and memory chips necessary to add new functions to theexisting module, and the adapter contains all information and hardwareneeded for proper interface with the computer system through themotherboard. A variety of functions such as parity, error correctioncode, error correction code on SIMM and double or triple redundancy canbe added to existing SIMMs which lack these functions by application anduse of the present invention. Also, the invention provides for changingvoltage levels when the interface types between the SIMM and the systemare different. Thus, existing SIMMs can be upgraded and still utilizedin a computer system without having to be entirely replaced anddiscarded in order to upgrade a computer system.

Therefore, it is an object of the present invention to provide thememory card adapter which has an edge connector for plugging a memorycard adapter into a memory card receiving socket located on a computersystem's motherboard, the memory card adapter also having a connectorsocket for receiving an in-line memory module or memory card.

It is a further object of the present invention to provide a memory cardadapter with features such as parity, ECC, or ECC on board beingincluded on the adapter so that these functions can be added to acomputer system without discarding the system's existing memory modules.

It is yet another object of the present invention to provide a memorycard adapter with added features that are compatible with a computersystem's existing memory modules while also having logic and memory tocontrol and communicate with the added features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a memory card adapter according to this invention containingadditional memory for parity;

FIG. 2 is a memory card adapter according to this invention havingadditional memory for check bits and a system for writing and readingcheck bits and performing ECC functions; and

FIG. 3 is a memory card adapter for translating signal voltage levelswhen the interface between the system and the SIMM are different.

DETAILED DESCRIPTION OF THE INVENTION

The present invention can exist in any number of environments, but willbe described in the context of an IBM Personal Computer using an Intel80486 or Pentium® microprocessor and with Dynamic Random Access Memory.Embodiments are provided of the present invention utilizing singlein-line memory modules ("SIMMs"), however it is contemplated the dualin-line memory modules ("DIMMs") could also be used with the presentinvention, or subsequently developed memory modules.

The present invention provides a memory card adapter 10 in which theadapter provides added features to a computer system without requiringthe replacement of the computer system's existing memory cards.

As best seen in FIG. 1, a memory card adapter 10 of the presentinvention is provided having a bottom edge having an electrical edgeconnector 12 thereon to plug into a card socket of a motherboard of acomputer system 13, and a top edge having a card receiving socket 14thereon. In an embodiment capable of accepting SIMMS, the electricaledge connector is a 72 pin SIMM edge connector and the card receivingsocket 14 is a 72 pin SIMM receiving socket. Furthermore, as shown inFIG. 1, the adapter 10 has four parity DRAMs 16 included on the adapter.The parity DRAMs 16 are the same address dimension as that of theexisting SIMM which is to be plugged or inserted into the card receivingsocket of the adapter 10. This embodiment is used when the systemgenerates and checks parity bits.

All address and data control lines 18 are routed from the electricaledge connector 12 of the adapter 10 directly to the SIMM receivingsocket 14 so that when the existing SIMM is plugged into the adapter 10,and the adapter 10 is plugged into the motherboard, the SIMM receivessignals from the computer system just as if it were directly pluggedinto the socket on the motherboard of the computer system. While theSIMM inserted into the adapter 10 receives signals from the computersystem via the adapter's SIMM receiving socket, minor propagation delaymay occur at times when sending a signal from the system through theadapter 10 to the SIMM. Also, when control signals are sent from thecomputer system through the adapter 10 to the SIMM, these controlsignals are tapped into by the adapter 10 for the purpose of controllingparity DRAMs 16 located on the adapter.

Additionally, the parity DRAMs 16 of the adapters have parity datainput/output ("PQ"s) 19 which are directly wired to the electrical edgeconnector 12 of the adapter so that the parity DRAMs 16 may access andprovide data to and from the system. The data input/outputs ("DQs") 20of the SIMM are not affected by the PQs 19 and are passed directly fromthe electrical edge connector 12 to the SIMM receiving socket and on tothe SIMM.

To further demonstrate how the parity adapter 10 embodiment works, ifthe existing SIMM, which lacks parity, is a 4Mx32 SIMM, the parity DRAMs16 on the adapter can be industry standard 4Mx1 DRAMs. After the adapter10 is plugged into the motherboard, each parity DRAM 16 on the adapterreceives addresses, column activation strobe ("CAS"), row address strobe("RAS") and write enable ("WE") from the motherboard of the computersystem. For example, the first DRAM on the adapter, whose parityinput/output is P0, receives CAS0, which controls byte 0 on the SIMM.Thus, the remaining DRAMs 16, P1 through P3, receive the correspondingCAS lines and accordingly control the corresponding byte. Thus, the4Mx32 architecture of the SIMM as manufactured is maintained, but parityis added. By adding parity to the SIMM, the computer interfaces with theadapter/4Mx32 SIMM assembly as if it were a 4Mx36 SIMM with parity.Thus, the capabilities and functions of the system are improved byadding parity to the SIMMs but without the expense of discarding andreplacing the SIMMs configured for parity.

In another embodiment, the adapter card 10 is used to form a x36 or x40ECC SIMM. To yield the ECC SIMM, the electrical edge connector 12 andSIMM receiving sockets 14 are identical to those utilized by the parityembodiment of the present invention. In the ECC SIMM embodiment,however, the adapter has one or two x4 DRAMs located on the adapter.These DRAMs have DQs wired to appropriate tabs on the 72-pin electricaledge connector. Also, the CAS lines are all dotted together so that CAS0drives all the DRAMs on the adapter and not just byte 0 of the DRAMs.This embodiment also is for use with a system which performs ECCfunctions.

FIG. 2 illustrates yet another embodiment in which an industry standardx32 SIMM is retrofitted with an ECC-on-SIMM adapter 10 to performon-board ECC. This adapter is for use on a system that does not havenative ECC capabilities. As seen in FIG. 2, to retrofit the x32 SIMM,each byte of data on SIMM 21 having DRAM 22 for data storage requires anadditional 4 bits of checkbit DRAM. SIMM checkbit DRAM 23 is provided atthe same address depth as the x32 DRAM 22 on the SIMM 21. The remainingthree bytes (not shown) of SIMM 21 have identified additional checkbitDRAM (not shown) added to adapter 10.

Furthermore, to yield an ECC-on-SIMM, each byte of data passes throughECC logic which is located in an ASIC 24 ("application specificintegrated circuit") on the adapter 10. Each byte of data passes throughthis ECC logic so either four low-pin-count ASICs or a singlehigh-pin-count ASIC are workable. As illustrated by FIG. 2, systemaddresses and control pass through the adapter to the existing SIMM, andare also tapped into by both the DRAMs 23 and ASIC 24 of the adapter 10.Also, the system data is passed from the motherboard to the ASIC 24 ofthe adapter which then passes the data bits to the appropriate DQs onthe DRAMs on the SIMM. Finally, the checkbit DRAMs of the adapter are incommunication with the ASIC. Thus, in this embodiment ECC functions areperformed by the ECC logic contained in the ASIC 24 (which logic is wellknow, e.g. of the type described is commonly assigned U.S. Pat. Nos.5,450,422 and 5,465,262 both of which are incorporated herein byreference) and data that has become corrupted after writing to the SIMM21 is corrected on a subsequent read cycle. It is to be understood thatin the same manner generating and checking parity can be performed byusing an ASIC with parity generating with check logic in conjunctionwith the DRAM for storage of checkbits. An interface for changing signalvoltage levels when the interface types between the SIMM and the systemare different is illustrated by FIG. 3. This embodiment provides for anadapter card/SIMM assembly that allows for different interface voltagelevels between the existing SIMM and the system. In this embodiment, theadapter 10 allows the system voltage levels which are GTL ("GunningTransistor Logic") to be translated to the x32 SIMM levels which are TTL("Transistor--Transistor Logic"). The adapter has level translationchips 26 in which system control signals pass from the motherboard tothe voltage translation chips 26 where the control signals aretranslated to the SIMM TTL level and then sent to the SIMM. Also, thesystem DQs are translated to SIMM 21 levels by level translation chip 28on the adapter 12 before passing to DRAMs 30 of the SIMM 21. Thetranslation may be uni-directional or bi-directional, with the TexasInstruments SN74GTL16612 18-Bit GTL/LVT Universal Bus Transceiver beingan example of an acceptable level translation device.

Another embodiment includes the addition of identification circuitry,such as a serial presence detect (SPD) erasable programmable read onlymemory (EPROM), that contains information different than what iscontained on the SIMM's 21 SPD EPROM, when such different information isrequired by the using computer system to distinguish between theoriginal function of the SIMM (e.g. non-parity) and the new function(e.g. parity) provided by the adapter and original SIMM together.

While the present invention has been illustrated by the description ofthe embodiments thereof, and while these embodiments have been describedin considerable detail, it is not the invention to restrict or in anyway limit the scope of the appended claims to such detail. Additionaladvantages and modifications may readily appear to those skilled in theart such as battery back-up for non-volatile operation, multiple SIMMsockets etc. Therefore, the invention, in its broadest aspects is notlimited to the specific details, the representative apparatus, or theillustrative examples shown and described. Accordingly, departures maybe made from such details without departing from the spirit or scope ofthe applicants' general inventive concept.

We claim:
 1. A memory card adapter device comprising:a) a printedcircuit board with at least one contact thereon insertable into a memorymodule socket of a motherboard; b) a memory module receiving sockethaving the same configuration as said memory module socket on themotherboard located on said printed circuit board configured to retain amemory module; c) at least one electrical device on said printed circuitboard having functionality not contained on the memory module; and d)circuitization including circuitry electrically connecting said at leastone electrical device to said memory module receiving socket on saidprinted circuit board and said at least one contact.
 2. The memory cardadapter device of claim 1 wherein said at least one electrical device onsaid printed circuit board is a parity DRAM.
 3. The memory card adapterdevice of claim 2 further comprising parity data input/output linesconnected to said at least one contact.
 4. The memory card adapterdevice of claim 1 wherein said at least one electrical device is a DRAMcapable of receiving and retaining ECC check bits.
 5. A memory cardadapter device including a printed circuit board insertable into amemory card socket in a motherboard comprising:a) said printed circuitboard containing a memory card receiving socket for retaining a memorycard; b) said printed circuit board having at least one connectorconfigured to be inserted into a memory card socket of a motherboardhaving the same configuration as the memory card socket on the printedcircuit board; c) data lines on said printed circuit board routed fromsaid connector to said memory card receiving slot on said printedcircuit board; and d) control lines routed from said connector to thememory card receiving slot on said printed circuit board, whereincontrol signals sent on the control lines are tapped into by theadapter.
 6. The memory card adapter device of claim 5 further comprisingparity DRAMs located on the printed circuit board and in communicationwith said at least one connector and the card receiving socket on saidprinted circuit board.
 7. The memory card adapter device of claim 6further comprising parity data input/output lines connected to said atleast one connector.
 8. The memory card adapter device of claim 5further comprising DRAMs capable of receiving and retaining ECC checkbits located on the adapter and in communication with said at least oneconnector and the card receiving socket on said printed circuit board.9. The invention as defined in claim 1, wherein said at least oneelectrical device includes circuitry to generate and read ECC bits andperform error correction function.
 10. The invention as defined in claim2, wherein said at least one electrical device generates and checksparity bits.
 11. The invention as defined in claim 1, wherein said atleast one electrical device includes circuitry to change signalinglevels between said memory modules and said motherboard.
 12. A computersystem and memory card adapter device comprising:a) said memory cardadapter device having a printed circuit board with at least one contactthereon inserted into a memory module socket of the computer system; b)a memory module receiving socket having the same configuration as thememory module socket of the computer system located on said printedcircuit board configured to retain a memory module; c) at least oneelectrical device on said printed circuit board having functionality notcontained on the memory module; and d) circuitization includingcircuitry electrically connecting said electrical device to said memorymodule receiving socket on said printed circuit board and said at leastone contact.
 13. A computer system and memory card adapter deviceinserted into a memory card socket of the computer system:a) said memorycard adapter having a printed circuit board containing a memory cardreceiving socket having the same configuration as the memory card socketof the computer system for retaining a memory card; b) said printedcircuit board having at least one connector configured to be insertedinto said card socket of said motherboard; c) data lines on said printedcircuit board routed from said connector to said memory card receivingslot; and d) control lines on said printed circuit board routed fromsaid connector to said memory card receiving slot, wherein controlsignals sent on the control lines are tapped into by the adapter. 14.The invention of claim 13 further comprising parity DRAMs located on theprinted circuit board and in communication with said at least oneconnector and the memory card receiving socket on said printed circuitcard.
 15. The invention of claim 14 further comprising parity datainput/output lines connected to said at least one connector.
 16. Theinvention of claim 13 further comprising DRAMs capable of receiving andretaining ECC check bits located on the adapter and in communicationwith said at least one connector and the memory card receiving socket onsaid printed circuit board.
 17. The invention as defined in claim 12,wherein said at least one electrical device includes circuitry togenerate and read ECC bits and perform error correction function. 18.The invention of claim 12 wherein said at least one electrical device isa parity DRAM, and said circuitization includes circuitry to connectsaid memory module receiving socket on said printed circuit board andsaid at least one contact.
 19. The invention of claim 18 furthercomprising parity data input/output lines connected to said at least onecontact.
 20. The invention of claim 12 wherein said at least oneelectrical device is a DRAM capable of receiving and retaining ECC checkbits.
 21. The invention as defined in claim 18, wherein said at leastone electrical device generates and checks parity bits.
 22. Theinvention as defined in claim 12, wherein said at least one electricaldevice includes circuitry to change signaling levels between said memorymodules and said motherboard.